Research on the genetics and physiology of Salmonella typhimurium will deal especially with three topics: (i) Lipopolysaccharide and other components of bacterial surface; especially mapping of rfa genes, determining structure of LPS core, determination of nature of defects in "part-rough" mutants, and testing of effect of such mutations on (mouse) virulence. (ii) Genetics and physiology of motility and chemotaxis, especially correlation of relevant genes in Salmonella and Escherichia, attempt to identify products of fla (flagella production) and che (chemotaxis) genes. (iii) Genetics and behavior in S. typhimurium of R (antibiotic resistance) and colicine factors, especially mapping of genes of plasmid R46 which determine its UV-protecting and mutator properties.